Yeah I noticed this myself and was a bit confused. Just based on code inspection, we’re pretty transparently passing the value from the CoreAudio callback back as provided by the API, so I don’t know if it’s really possible that we’re munging this here. However, these CA API’s use reference-as-return-value call semantic, which means if they error out they COULD be leaving the variable in an undefined state. I’d have to check, but it might be that this case is simply CA erroring at our obviously bogus request of 1 sample, and then us printing some uninitialized value from memory (which happens to be 15 - because uninitialized values are ALWAYS something confusingly close to what you expected 
)